One type of moisture detector for measuring the moisture content of wood uses an alternating current (AC) signal. The AC signal is generated by an oscillator circuit in the moisture detector and drives a detector circuit. This type of moisture detector also includes a sensor connected to the detector circuit which comprises a pair of electrodes, a detector electrode and a common electrode, that are typically plate-shaped. When the sensor is placed in close proximity to an object whose moisture is to be measured, the impedance between the electrodes is related to the moisture content of the wood. The impedance between the electrodes is sensed by the detector circuit using the AC signal to determine the moisture content of the object.
In one known prior moisture detector, a detector circuit is used that includes a transformer to couple the AC signal to the detector electrode. Generally, with a transformer, the circuit must be manually assembled, resulting in a more costly manufacturing or assembly process. Also, transformers are expensive circuit components. Therefore, because of the transformer, the cost of the detector circuit is considerably more than it would otherwise be.
It is therefore an object of the present invention to provide an improved moisture detector for detecting the moisture content of wood or other structural materials.
It is another object of the invention to provide such a moisture detector for detecting the moisture content of roofs or walls or other building components.
Yet another object of the invention is to provide an improved moisture detector circuit for use in moisture detectors that does not require a transformer.
It is a further object to provide a detector circuit that can be machine assembled and is constructed of relatively inexpensive components.